Multiple processes turn logs into finished wood products for consumers. One important process involves using a log saw to cut a large log into smaller sections of predetermined lengths for ease of handling and further processing. Log saws may be stationed at a variety of locations in a mill. When used in a veneer mill, log saws typically are stationed after a debarking machine, which takes the bark off of a log, and before a veneer lathe, which peels a long veneer strip from the log.
To minimize waste, is important that the log saw cut the log in a cutting plane perpendicular to a central longitudinal axis of the log. If the log saw cuts the log in a cutting plane that is askew relative to the central longitudinal axis of the log, the log typically will is have to be squared off by a separate machine before further processing, thereby consuming unneeded time and energy and wasting valuable wood product material.
In a veneer mill, typically the veneer lathe will square the log off with a pair of facing tools positioned near each end of the log. These facing tools typically cause pitting in the ends of the log as they cut across softer and harder regions of the end g of the log. As the veneer lathe peels a sheet of veneer from the log section, the pitted ends of the log will translate into pitted sides on the veneer sheet.
Often, logs fed to a log saw for sectioning will be tapered in shape, with a wide base, a narrow top, and tapered sides extending therebetween One problem with cent log saws is that they typically are unable to center a tapered log such that the log saw may be cut in a cutting plane perpendicular to the central longitudinal axis of the log. Log saws equipped with horizontal planes of su t normally will hold a tapered log such that the central longitudinal axis of the tapered log extends at a slight incline relative to the plane. In this case, a saw blade that is perpendicular to the plane of support Will cut the log in a cutting plane that is inclined to the central longitudinal axis of the log, thereby necessitating that the tapered log be squared off by a separate machine, as described above.
Certain log saws have been designed with an inclined conveyor for moving a tapered log into a cutting station such that the central longitudinal axis of the tapered log is normal to the plane of cutting. However, these devices generally are cumbersome, slow in operation, and designed to handle logs of similar size that are oriented with their tapers extending in the same direction.
In addition, a log saw is most efficient when it is capable of analyzing a log, and applying a predetermined formula to determine the optimum number and length of sections to cut from the log Current log sawing systems utilize a three dimensional scanner and associated computer software to determine optimum section lengths. A saw operator reads the section lengths, adjusts a mechanical stopper to the specified distance, then feeds the log through the saw until an end of the log rams the stopper. The operator cuts the log and readjusts the stopper to repeat the cycle.
This process is arduous on the operator and the machinery. Great impact forces are produced as the logs ram against the stop, necessitating the use of ear protection by the operator, and causing wear on the machine. In addition, operator error may cause the stopper to be placed out of position, and the log to be miscut.
In addition, a log saw is most efficient when the cycle time of the saw blade during each cut is minimized. Cycle time for a cut primary is affected by movement of the log and movement of the saw blade. Current log saws typically accelerate a log from a full stop, move the log into the machine, and bring the log back to a full stop in position for cutting. When attempting to operate a log saw at high speeds, bringing the heavy log to a complete stop takes valuable time and energy. In addition, time typically also is wasted on each cut cycle while waiting for the log to bounce repeatedly against the stop before coming to a rest.
Current saw blades often require the saw blade to travel the same distance on each cut regardless of the diameter of the log being cut, wasting time and energy when cutting logs of smaller diameter. This is because current log saws typically position both small and large logs such that the bottom of the log rests near the bottom of the circular saw blade when the log is being cut. In such a configuration, moving the saw blade from a retracted position to an extended position where the bottom of the saw blade cuts completely through the bottom of the log requires the saw blade to travel a distance significantly greater than the diameter of smaller logs.